In vitro quality parameters of whole blood-derived platelets pooled using two different platelet pooling sets and stored up to 7 days are similar.

BACKGROUND: Increasing the number of collections of whole blood-derived platelets (WBDP) and lengthening the allowable storage time may alleviate platelet (PLT) shortages. There is a need for new PLT pooling sets that can provide acceptable quality on Day 7 of storage. STUDY DESIGN AND METHODS: This pool-and-split study compared WBDP prepared using the platelet-rich plasma method with the novel IMUGARD WB PLT pooling set and a control pooling set. After pooling and filtration, PLT products were tested on Days 1, 5, and 7. Large volume delayed sampling (LVDS) cultures were taken on Day 2. RESULTS: The median postfiltration residual white blood cell (rWBC) content was 0.18 million per product (maximum 1.26 million; n = 69) with mean PLT recovery of 88.5 ± 2.8% for the new set and median 0.23 million (maximum 1.83 million) rWBC with 87.5 ± 2.5% recovery for the control. Day 5 mean pH22°C were 7.18 ± 0.12 and 7.13 ± 0.10 for the new and control set, respectively. Day 5 in vitro quality parameters were within 20% between the two pooling sets. The new set Day 7 pH22°C was acceptable (7.07 ± 0.17, 100% ≥ 6.3), and most parameters were within 20% of Day 5 values. CONCLUSION: WBDP quality for the new pooling set is acceptable across a battery of in vitro tests when stored up to 7 days and meets FDA regulatory criteria. The quality parameters were similar between the new pooling set and the control set on Day 5. This new set is compatible with LVDS.

A flow cytometric method for platelet counting in platelet concentrates.

BACKGROUND: The platelets (PLTs) in PLT concentrates are counted with hematology analyzers, but varying results among different hematology analyzers are observed, making comparisons very difficult. Due to the absence of red blood cells in PLT concentrates, the International Council for Standardization in Hematology (ICSH) reference method was modified to be used for PLT concentrates and validated in an international comparative study. STUDY DESIGN AND METHODS: Five PLT samples were shipped to eight participating centers of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative and counted on the same day. PLTs were stained with fluorescein isothiocyanate-labeled anti-CD41a in tubes (TruCount, BD Biosciences), measured on a flow cytometer, and analyzed with a uniform template. These samples were also counted on 15 hematology analyzers. RESULTS: The ICSH method and newly developed BEST method yielded PLT counting results with less than 1% difference (not significant). The intercenter coefficient of variation (CV) of the BEST method was on average 6.3% versus 7.6% on average for hematology analyzers. The CV of individual hematology analyzers was on average 0.9%, which was considerably lower than for the flow cytometers with a mean of 3.7%. CONCLUSION: The BEST flow cytometric method has a smaller intercenter CV and a smaller center-to-center deviation from the group mean compared to hematology analyzers. Conversely, individual hematology analyzers are more precise than the flow cytometric method. Thus, the flow cytometric method provides a calibration tool to allow comparisons between centers, but there is no need to replace routine counting with hematology analyzers.

Interruption of agitation of platelet concentrates: a multicenter in vitro study by the BEST Collaborative on the effects of shipping platelets.

BACKGROUND: Transported platelets (PLTs) are not under continuous agitation. The aim of this study was to determine whether PLTs shipped between 24 and 48 hours would be able to maintain a pH(22 degrees C) value of 6.5 at the end of 7 days of storage. STUDY DESIGN AND METHODS: Six laboratories prepared leukoreduced PLTs. PLT pools were divided into low and high PLT concentration with paired shipped (20-43 hr) and unshipped controls. Units were under continuous agitation at 22 +/- 2 degrees C when not being transported. In vitro measures including pH, pO(2), and pCO(2) were determined over 7 days. RESULTS: Ninety-two PLT components from 24 pools were eligible for analysis. One unshipped control and three shipped products failed to maintain a pH(22 degrees C) value of 6.5 through 7 days. In vitro characteristics were maintained slightly better over 7 days of storage in the unshipped control arms. PLT concentration, shipping time, and their interaction were significant determinants of the final pH at the end of storage (p < 0.05). Lactate generation rate increased by 35 +/- 2 (mean +/- SE) micromol per 10(12) PLTs per hour over baseline during shipping (p < 0.0001). After restoration of standard blood banking conditions with agitation, this rate dropped 24 +/- 2 micromol per 10(12) PLTs per hour (p < 0.0001). CONCLUSION: PLTs in plasma shipped for at least 20 to 24 hours maintain a pH(22 degrees C) value of 6.5 for 7 days. A longer shipping time may result in a pH(22 degrees C) value of 6.5. During shipping, glycolysis was up regulated in these PLTs resulting in increased lactic acid production. After restoration of agitation, shipped products down regulated glycolysis. These effects should be accounted for in the development of PLT storage and transportation systems.

Seven-day storage of apheresis platelets: report of an in vitro study.

BACKGROUND: The objective of this study was to determine the allowable platelet content limits for apheresis platelets stored for 7 days in a platelet storage bag (COBE ELP, Gambro BCT). METHODS: Apheresis platelets under controlled concentration and volume per bag were stored in plasma up to 8 days at 22 degrees C with horizontal agitation. Routinely evaluated in vitro platelet parameters were followed. Oxygen consumption was directly measured with a Clark-type electrode. All components were cultured in aerobic medium on Day 7. RESULTS: Twenty-four components were evaluated in storage configurations (median [range], 340 [110-402] mL, 1.32 [0.99-2.45] x 10(6) platelets/microL, and 4.8 [1.4-5.9] x 10(11) platelets/bag). No bacterial contamination was detected. One component had a pH value at 22 degrees C of below 6.0 before Day 5 with attendant loss of all other in vitro function measures. The pH value at 22 degrees C was maintained above 6.2 for the remaining 23 components. A pH value of greater than 7.4 was observed at some point in storage for 13 of 23 units, although platelet function or activation was not adversely affected. Aerobic metabolic function was maintained over 7 days with O2 consumption of 321 micromol per hour per 10(12) platelets on Day 7. CONCLUSION: Although a continuing decline of platelet in vitro characteristics can be observed for storage beyond 5 days, apheresis platelets in plasma stored 100 to 400 mL per bag, 1.0 x 10(6) to 2.5 x 10(6) platelets per microL, and a maximum of 5.1 x 10(11) platelets per bag maintained in vitro platelet characteristics over 7 days of storage.